The last three decades has seen considerable effort in the development of improved methods for the isolation and purification of nucleic acids. This has been due mainly to the increasing applications of nucleic acids in the medical and biological sciences. Genomic DNA isolated from blood, tissue or cultured cells has several applications, which include PCR, sequencing, genotyping, hybridization and southern blotting. Plasmid DNA has been utilized in sequencing, PCR, in the development of vaccines and in gene therapy. Isolated RNA has a variety of downstream applications, including in vitro translation, cDNA synthesis, RT-PCR and for microarray gene expression analysis.
The analysis and in vitro manipulation of nucleic acids is typically preceded by an isolation step in order to free the samples from unwanted contaminants which may interfere with subsequent processing procedures. For the vast majority of procedures in both research and diagnostic molecular biology, extracted nucleic acids are required as the first step.
The increased use of DNA and RNA has created a need for fast, simple and reliable methods and reagents for isolating DNA and RNA. In many applications, collecting the biological material sample and subsequent analysis thereof would be substantially simplified if DNA and RNA could be simultaneously isolated from a single sample. The simultaneous isolation is especially important when the sample size is so small, such as in biopsy, that it precludes its separation into smaller samples to perform separate isolation protocols for DNA and RNA.
Also needed is an improved process for separating double-stranded from single-stranded nucleic acids in general. Many nucleic acid molecular biology experiments start from purified nucleic acids and produce a mixture containing both. A separation step is required at the end of many of these experiments and sometimes both the single-stranded and the double-stranded nucleic acids need to be recovered for further analysis.
Currently, the silica membrane column format is widely used for separating and isolating double-stranded and single-stranded nucleic acids. However alcohol is required as a binding reagent, which posts a safety concern as it is flammable.
A novel and advantageous method for carrying out separation and isolation of double-stranded and single-stranded nucleic acids from the same sample is presented herein.